Early in the second quarter Saturday night, 49ers running back Kendall Hunter took a handoff from Alex Smith, pinballed off Texans linebackers Brian Cushing and Bradie James and churned forward - pushing cornerback Jonathan Joseph back in the process - before he was brought down for a 6-yard gain.

Nearly six minutes later, Hunter - all 5-foot-7 and 199 pounds - darted right, ran through an arm tackle by James at the line, zipped into the secondary and capped a 14-yard run by dragging 287-pound Jared Crick the final few yards.

In the stands at Reliant Stadium in Houston, Thomas Brooks, Hunter's former high school coach, was having flashbacks.

To Brooks, the early stages of Hunter's second season in the NFL resemble his senior year at John Tyler (Texas) High, where he broke the school rushing record held by Hall of Famer Earl Campbell.

"I thought he looked more explosive than he did last year," Brooks said. "He's used to the speed of the game and looked more comfortable. I was very impressed with the way he was running; that looked like his senior year in high school. ... I saw the cuts. That looked like the confidence he had when he was running in high school."

Of course, Brooks, now an assistant at Katy High outside Houston, watched Hunter's rookie season from afar. But those who have seen his development up close have offered a similar analysis.

After earning training-camp raves from head coach Jim Harbaugh, Hunter's performance has carried into the preseason. In two games, he has 70 yards on 11 carries, flashing decisiveness, quickness and Herculean lower-body strength that belies his size.

"You can tell that from his first year to this year that he grew a lot," 49ers running back Frank Gore said. "It's his second year in the offense. He knows what he's doing now. He's not thinking. He's just playing football, and that's what he's good at."

Hunter clearly has retained his status as the primary backup to Gore even after the 49ers added to the backfield in the offseason by signing Brandon Jacobs and drafting Oregon's LaMichael James in the second round.

And it's possible Hunter's role will expand as San Francisco looks to keep Gore, 29, fresh throughout the season. Gore played in 16 games for the second time in his seven-year career in 2011, but ankle and knee problems limited his effectiveness down the stretch: He averaged 3.5 yards a carry and 53.6 yards in the final eight regular-season games.

Hunter is ready to assume a larger load.

As a rookie, he was transitioning to a pro-style offense after playing in a spread attack at Oklahoma State. In addition, the lockout condensed his learning time, which had him experiencing pre-snap anxiety during games.

Asked what was racing through his mind as he broke the huddle last year, Hunter laughed as he delivered the punch line: "Uh-oh," he said.

Still, Hunter was no slouch. He collected 668 yards from scrimmage while averaging 4.2 yards a carry and 12.2 yards on 16 receptions.

A year later, he's poised to contribute even more. He's gone from "uh-oh" to feeling OK.

"I'm still learning it, but I've kept working hard and things have gotten better," Hunter said.

"Things have slowed down and hopefully things will slow down even more. I feel like I know more of what I'm doing out there, and I don't have to think so much."